Heating system



H. J. DE N. M COLLUM HEATING SYSTEM Filed Feb. :5, 1941 April 28, 1942.

Patented Apr. 28, 1942 UNITED STATES PATENT OFFICE.

HEATING SYSTEM Henry J. De N. McCollum, Chicago, Ill.

Application February 3,1941, Serial No. 377,182

8 Claims.

, engine supercharger, and which is simple to construct, easily installed, and is safe and reliable in operation.

Another object of my invention is to provide an improved internal combustion heating system which is supplied with combustible mixture directly from an internal combustion engine supercharger.

A further object of my invention is to provide an internal combustion heating system comprising a plurality of heaters having individual electric operating circuits, with an improved electrical control system whereby the operating circuit of each heater is energized incidental to supplying combustible mixture to the heater.

A further object is to provide an improved safety control circuit for a heating system comprising a plurality of internal combustion heaters whereby the supply of combustible mixture to the system is discontinued upon the overheating of one of them. 7

A further object is to provide an improved control mechanism for a heating system comprising two internal combustion heaters, whereby either or both heaters may be supplied with combustible mixture, and the operating circuit of each heater is energized only when that heater is supplied with combustible mixture.

In previous internal combustion heating systerns, a separate, heating system carburetor is usually provided, and a blower is sometimes used to cause combustible mixture to flow to the heater. My improved heating system receives combustible mixture from the engine supercharger and makes use of the pressure differential created by the supercharger to cause combustible mixture to flow to the heaters and the products of combustion to flow therefrom, thereby making the system positive in its operation and rendering the use of a separate carburetor, or a blower to operate the heater, unnecessary.

Other objects will appear from the following description, reference being had to the accompanying drawing in which:

Fig. 1 is a diagrammatic representation of my improved heating system, comprising two heaters installed in an airplane;

Fig. 2 is a cross-sectional view of the fitting used to remove combustible mixture from the engine intake manifold; and

Fig. 3, is a cross-section of the fitting used to discharge the combustible mixture into the engine supercharger intake.

Referring to Fig. 1, arrows indicate the direction of flow of fluid through the respective conduits. The engine supercharger i0 is operated by the airplane engine to withdraw combustible mixture from the engine carburetor I2. An inlet fitting M extends a short distance into one of the engine intake manifolds it which connects the supercharger H) with the engine cylinders. A conduit connects the fitting M with the inlet port 21 of the valve chamber 54 of a manually operable three-way valve assembly is. Conduits 2d and 26 connect the outlet ports and .21 of the valve chamber 54 with the combustion chambers 32 of the heaters 28 and 30, respectively. The heaters 28 and 30 maybe of the general type disclosed in my prior Patents No. 2,191,- 1'73, issued February 20, 1940, and No. 2,192,688, issued March 5, 1940. Each heater comprises a shelf enclosing a combustion chamber 32, a heat exchanger receiving the products of combustion therefrom, and an electric motor 30, operating a fan to blow air past the heat exchanger, thereby heating the air. Conduits 36 and 38 connect the outlets of the heaters 28 and 30, respectively, with a Y-fitting 40 which is attached to the heating system exhaust conduit; 42. A flexible coupling 44 connects the outlet of the exhaust conduit $2 with an exhaust fitting 46 which extends into the intake conduit of the engine supercharger Ill.

A handle 48 may be rotated to position a valve 22 so that all of the ports 2], 25, and 2'1 are uncovered, or so that any one of the ports is covered. Thus, the valve 22 may be positioned to allow combustible mixture to flow to both heaters, to stop the flow of combustible mixture entirely, or to allow combustible mixture to flow to either heater alone.

The energization of the various control circuits and operating circuits of the heating system is controlled incidental to changing the position of the valve 22, as is hereinafter described. A circular cam plate 50 having a rise 52 is mounted for rotation with the valve 22, and arranged so that the center of the rise 52 is in substantially the same angular position as the center of the face of the valve 22., One of the cam followers each other.

56, engaging a resilient arm attached to a corresponding switch 58, 60, 62 is positioned opposite each of the ports 2|, 25, and 21 of the valve chamber 54. When the valve 22 is positioned to cover one of these ports, the rise 22 engages the corresponding follower 56 to separate the contacts of the corresponding switch. A resilient arm causes the switch to close when the rise 52 is not in contact with the follower 56 which operates the switch.

One terminal of a source of electric current 64 is grounded, and the other terminal is electrically connected with the live contact of the master switch 58. The operating circuits of the individual heaters 28 and 38 are electrically connected in parallel and are connected in series with the movable contact of the master switch 58. In each individual heater circuit is a switch 60, 62 which controls the energization of that circuit. Thus, when the valve 22 is positioned to cover the port 2| and prevent the fiow of combustible mixture to the system, the rise 52 engages the follower 56 to open the switch 58 and discontinue the energization of both heaters. When the valve 22 is positioned to cover the port 25 and prevent the flow of combustible mixture to the heater 28, and to allow combustible mixture to flow to the heater 30, the rise 52 of the cam 50 engages the follower 56 to open the switch 60, thereby discontinuing the energization of the operating circuit of the heater 28. However, current may flow from the source of current through the master switch 58, through the switch 62, to the heater 30. When the valve 22 is positioned to cover the port 21, the switch 62 is opened in a similar manner to discontinue the supply of current to the heater 30, While the master switch 58 and the switch 50 remain closed to supply current to the heater 28.

A solenoid controlled safety valve 65 is provided to stop the flow of combustible mixture through the conduit when the heater circuits are de-energized, or when either of the heaters overheats. A solenoid winding 66 is also in series with the master switch 58 and the valve 65 is arranged to open when the solenoid winding 66 is energized, and to close itself when the winding 66 is not energized. Normally closed thermostatic safety switches 68 and I0, responsive to the temperature of the heaters and respectively, are electrically connected in series with thejolenoid 7 These thermostatic switches 68, III are adjusted to open when the temperature of the corresponding heater 28, 30 rises above a predetermined safe maximum value. Overheating of either heater will cause one of the thermostatioswitches 68 or III to open, opening the circuit of the solenoid winding 66, and allowing the valve 65 to close. Opening of the master switch 58 also will discontinue the energization of the solenoid winding. Thus, when the port 2| is covered by the valve 22, no current fiows to the heating system.

When the engine is in operation, a film of liquid fuel and engine lubricant covers the inner surface of supercharger I 0 and the engine intake manifold I6. For this reason, it is very desirable to withdraw combustible mixture from a point in the intake manifold where there is no danger of this surface film passing into the intake line of the heating system. This is accomplished by the use of an intake fitting I4 which extends a short distance into the interior of the manifold I 6.

As is shown more clearly in Fig. 2, the inlet end of the combustible mixture intake fitting I4 has external threads 14 which engage a correspondingly threaded drilled and tapped hole 16 in the engine intake manifold I6. The open end of the fitting I4 which extends into the intake manifold I6 is preferably square so that the intake opening is substantially parallel to the direction of fiow of combustible mixture to the engine. If this fitting I4 opened obliquely facing the flow of combustible mixture in the intake manifold, the globules of lubricant and fuel entrained in the combustible mixture flowing through the manifold I6 would tend to pass into the central passage 12 of the fitting I4. If the fitting I4 opened in the opposite direction, the

pressure of the combustible mixture passing to the heating system would be decreased by an amount equivalent to the velocity head of the combustible mixture fiowing within the intake manifold I6. By providing a square inlet end extending into the intake manifold I6, the passage of liquids into the central passage 12 of the fitting I4 is substantially eliminated, inasmuch as the liquids tend to adhere to the surface of the manifold I6. Those particles of liquid that are entrained in the combustible mixture tend to pass directly past the inlet of the intake fitting I4. Therefore, the combustible mixture passing to the heating system is relatively free from liquids which would interfere with the operation of the heaters.

The flexible conduit I8 is conveniently attached to the fitting I4 by placing it over a tubular extension I8 which has peripheral grooves therein for retaining the conduit in place. The conduit is tightly retained to the extension 18 by a suitable clamp 82 and frictionally held in place. A hexagonal collar 84 is conveniently formed around the fitting I4 between the threaded inlet end and the tubular extension to facilitate the insertion of the fitting I4 into the intake manifold I6.

As is shown in Fig. 3, the exhaust fitting 46,

5 which is formed in a manner generally similar to the fitting I4, is threaded into a drilled and tapped hole in the inlet conduit of the engine supercharger I0. However, the end of the fitting which extends into the supercharger inlet conduit is beveled and arranged so that the velocity of the combustible mixture passing into W thesuperchargercauses a decrease in the pressure within the internal passage 12 of the fitting 46. Other portions of the fitting 46 correspond to similar portions of the fitting I4 and are similarly numbered.

When the engine is running air is drawn through the carburetor where it mixes with fuel to form a combustible mixture, and the combustible mixture passes into the supercharger I0 where it is compressed. The mixture then passes through engine intake manifolds I6, to the cylinders of the engine. Thus, the combustible mixture at the open end of the fitting I4 is at a higher pressure than the combustible mixture at the open end of the fitting 46. When the heating system is not in operation, the valve 22 covers the port 2| to prevent combustible mixture from flowing to the heaters, and the rise 52 of the cam 50 engages the follower 56 to hold the master switch 58 open and prevent current from flowing through any of .the circuits of the heating system. To condition the heating system for operation, the handle 48 is actuated to move the valve 22 to uncover the port 21. This moves the rise 52 of the cam 56 out of engagement with the follower 56 of the master switch 58, and allows the master switch 58 to close. Current then flows from the source 64 through the master switch 58, through the thermostatically controlled safety switches 16 and 66, in series, and through the solenoid winding 66 of the safety valve 65. The flow of current through the solenoid winding 66 causes the valve 65 to open to allow combustible mixture to flow through the valve '65 and through the threeway valve assembly I 9 to the combustion chamber 32 of the individual heaters 28, 36. The closing of the switch 58 also permits current to flow through the individual heater switches 6|l and 62 to the operating circuits of the heaters 28 and 36, respectively. The combustible mixture in the combustion chambers 32 of each heater is ignited by an electrically operated igniter, and is burned. The motor 34 of each heater operates a fan which passes air through the heater to the space to be heated. The products of combustion from the heaters 28 and 30 pass through conduits 36 and 38 respectively, through the exhaust conduit 42, and through the fitting 46 into the supercharger inlet. The quantity of combustible mixture consumed by the heating system is so small in relation to the combustible mixture consumed by the engine that the operation of the heating system has no appreciable effect upon the performance of the engine.

If it is desired to-operate the heater 28 alone, the handle 48 is operated to' move the valve 22 to cover the port 21 and prevent combustible mixture from passing to the heater 30. When the valve 22 is in this position, the rise 52 of the cam 50 engages the follower 56 of the switch 62 and opens the operating circuit of the heater 30. However, current flows through the master switch 58 and the heater switch 60 to the heater 28, and through the safety switches 10, 68 to the solenoid winding 66.

If the heater 30 is desired to be operated alone, the valve 22 is positioned to cover the port 25, thereby preventing combustible mixture from flowing to the heater 28, and the rise 52 is thereby positioned to open the switch 60 and de energize the operating circuits of the heater 28. If desired, the valve 52 may be positioned to partially cover one of the ports 2|, 25, or 21 and the heating system will not operate at its full capacity.

If one of the heaters should fail to function properly and should become overheated, one of the thermostatic safety switches 68 or 10 will open, thereby opening the circuit of the solenoid winding 66 and allowing the safety valve 65 to close to prevent combustible mixture from flowing to the heating system.

The heaters will deliver a substantially uniform quantity of heat over most conditions of operation. When the airplane is cruising, the engine operates at a substantially constant speed, and inasmuch as the engine is usually directly connected with the supercharger, thesupercharger also operates at a constant speed The engine throttle valve controls the rate at which combustible mixture is supplied to the supercharger intake, and thus controls the vacuum within the supercharger assembly. However, when the pressure within the supercharger drops, the supercharger will create a substantially constant pressure diiferential between its inlet and outlet, irrespective of the absolute pressure. It is this pressure difierential, which remains substantially constant at a given engine speed, which causes combustible mixture to flow to the heater and the products of combustion to flow therefrom. The quantity of combustible mixture flowing to the heater is substantially proportional to the square root of the difference in pressure between the heater inlet and outlet. Inasmuch as the quantity of heat delivered by the heater is proportional to the amount of combustion mixture supplied to the heater, the heat output of the heater does not vary appreciably when the engine is operating at cruising speed.

While I have disclosed my invention in connection with a preferred embodiment thereof, it will be apparent to those skilled in the art that numerous departures may be made from the construction disclosed without departing from the underlying principles of my invention. I, therefore, wish to include within the scope of the following claims all constructions by which substantially the results of my invention are obtained by substantially the same or equivalent means.

I claim:

1. In a heating system for use in conjunction with an internal combustion engine receiving a compressed combustible mixture of fuel and air from a supercharger having an inlet and an outlet, the combination of an internal combustion heater, a conduit for supplying combustible mixture to said heater from said outlet, and a conduit for discharging the products of combustion from said heater into said inlet, whereby the differential pressure created by-said supercharger will cause combustible mixture to flow to said heater, and the products of combustion to flow therefrom.

2. In a heating system for use in conjunction with an internal combustion engine having a supercharger, a source of combustible mixture, a conduit connecting said source with the inlet of said supercharger, and an engine intake manifold for conveying combustible mixture from the outlet of said supercharger to the cylinders of said engine, the combination comprising an internal combustion heater having a combustion chamber, a tubular fitting extending a short distance through the walls of said manifold into the interior thereof, a conduit connecting said fitting with said combustion chamber for supplying combustible mixture thereto, and a conduit for discharging the products of combustion from said heater into the inlet of said supercharger. 3. In a heating system-for use in conjunction with an internal combustion engine having a supercharger, means for supplying combustible mixture to said supercharger and an intake manifold for supplying combustible mixture from said supercharger to the cylinders of said engine, the combination of an internal combustion heatercomprising a combustion chamber for burning combustible mixture and a heat exchanger receiving the products of combustion therefrom, an intake fitting extending through the walls of said intake manifold into the interior thereof and having an inlet opening disposed substan-- tially parallel to the direction of flow of combustible mixture through said manifold, a conduit connecting said fitting with said combustion chamber for supplying combustible mixture thereto, and a conduit affording communication between the outlet of said heat exchanger and the inlet of said supercharger for conveying the products of combustion from said heater.

4. In an internal combustion heating system for use in conjunction with an internal combustion engine having a supercharger, a source of combustible mixture, an intake conduit connecting said source with the intake with said supercharger, and an intake manifold for supplying combustible mixture from said supercharger to said engine, the combination of an internal combustion heater comprising a combustion chamber and a heat exchanger receiving the products of combustion therefrom, a tubular intake fitting extending a short distance into the interior of said manifold and having an inlet opening disposed substantially parallel to the direction of flow of combustible mixture through said manifold, a duct connecting said fitting and said combustion chamber, a tubular exhaust fitting extending a short distance into said intake conduit and having an outlet opening so disposed with relation to the flow of combustible mixture through said conduit that the velocity head of the combustible mixture therethrough causes a reduction in the pressure at the outlet of said fitting, and a conduit connecting the outlet of said heat exchanger with said last-named fitting.

5. In a heating system comprising a plurality of internal combustion heaters having a common combustible mixture supply conduit, and a common exhaust conduit, the combination of a solenoid operated valve for controlling the flow through said conduits, a solenoid winding which may be energized to open said valve, means for closing said valve upon the deenergization of said winding, a source of electric current for energizing said solenoid winding, a temperature responsive switch adjacent each of said heaters and responsive to the temperature thereof to open when said temperature rises above a predetermined maximum value, and electrical connections connecting said source of current, said switches, and said solenoid winding in series, whereby an overheating of one of said heaters will open one of said switches to discontinue the energization of said solenoid and allow said valve to close.

6. In a heating system for use in conjunction with an internal combustion engine having a supercharger compressing a combustible mixture of fuel and air, the combination of an internal combustion heater having a combustion chamber and a heat exchanger receiving the products of combustion therefrom, a duct for supplying combustible mixture to said combustion chamber from a point at which combustible mixture has been compressed by said supercharger, and a duct for conveying said products of combustion from said heat exchanger to a point where combustible mixture is maintained at a pressure less than at said first-named point by the action of said supercharger.

7. In a heating system comprising a plurality of internal combustionheaters, each oi? said heaters having an electrically operated device, a source of electric current, and electrical connections for energizing each of said devices from said source, the combination comprising a common conduit for supplying combustible mixture to said heaters, means for discharging the products of combustion from said heaters, a plurality of conduits for supplying combustible mixture from said common conduit to each of said heaters, a valve for controlling the flow of combustible mixture through said common conduit, a switch in series with said source of current and said electrically operated devices, and means for opening and closing said switch incidental to opening and closing said valve.

8. The combination of a plurality of internal combustion heaters, an electrical operating circuit for each of said heaters, a common conduii; for supplying combustible mixture to all of said heaters, a plurality of parallel conduits connecting each of said heaters with said common conduit, a source of electrical current, a common electrical conductor for supplying current from said source to all of said heaters, a plurality of parallel electrical conductors for supplying current from said common conductor to each of said electrical operating circuits, a master switch for directly controlling the flow of current through said common conductor, a plurality of switches, one in each of said parallel conductors, means for preventing the flow of combustible mixture through said common conduit, means for opening said master switch incidental f to preventing said flow, means for preventing the flow through one of said parallel conduits, and means for opening the switch in the corresponding parallel conductor incidental to preventing the flow of combustible mixture to the corresponding heater.

HENRY J. DE N. MCCOLLUM.

D! S CLAIM ER 2,281,107 .Henry J. De N. McO'ollum, Chicago, 111. HEATING SYSTEM. Patent dated April 28, 1942. Disclaimer filed August 20, 1943, by the inventor. Hereby enters this disclaimer to claims 1 and 6 of said patent.

[Qflic'ial Gazette September 28, 1943.] 

